Kostner K M, Maurer G, Huber K, Stefenelli T, Dieplinger H, Steyrer E, Kostner G M
Second Department of Medicine, University Hospital of Vienna, Austria.
Arterioscler Thromb Vasc Biol. 1996 Aug;16(8):905-11. doi: 10.1161/01.atv.16.8.905.
The biosynthesis and assembly of lipoprotein(a) [Lp(a)], a marker for atherosclerotic disease, appears to be well understood. However, information is lacking concerning the mode and site of Lp(a) catabolism. Apo(a) is reported to be excreted into the urine. To study the effect of this pathway on the overall catabolism of Lp(a), urinary apo(a) was characterized by immunoblotting. More than 10 distinct apo(a) bands with molecular masses between 30 and 160 kD were observed. Apo(a) fragments were not complexed to apoB. In more than 30 individuals the size of apo(a) bands was comparable irrespective of their apo(a) phenotype, although marked differences in the relative intensities of the bands were observed. Eight batches of 24-hour urine collections collected from one proband at 2-week intervals exhibited a significant correlation between creatinine and apo(a) concentrations as measured by DELFIA (r = .93; P < .01). In 193 healthy volunteers a highly significant correlation was found between urinary apo(a) concentrations normalized to creatinine levels and plasma Lp(a) values (p = 0.659; P < .0001). Of the total plasma apo(a), 0.073%, i.e., 121 micrograms apo(a), was excreted in the form of apo(a) fragments in 24-hour urine samples from 12 healthy volunteers. We conclude that the catabolism of Lp(a) via excretion of apo(a) fragments accounts for < 1% of the daily Lp(a) catabolism.
脂蛋白(a)[Lp(a)]作为动脉粥样硬化疾病的一个标志物，其生物合成与组装似乎已被充分了解。然而，关于Lp(a)分解代谢的方式和部位的信息却很匮乏。据报道，载脂蛋白(a)[apo(a)]可排泄到尿液中。为了研究该途径对Lp(a)整体分解代谢的影响，通过免疫印迹法对尿apo(a)进行了表征。观察到10多条不同的apo(a)条带，其分子量在30至160kD之间。apo(a)片段未与载脂蛋白B结合。在30多名个体中，无论其apo(a)表型如何，apo(a)条带的大小都是可比的，尽管条带的相对强度存在明显差异。从一名先证者每隔2周收集的8批24小时尿液样本中，通过时间分辨荧光免疫分析(DELFIA)测得的肌酐和apo(a)浓度之间存在显著相关性(r = 0.93；P < 0.01)。在193名健康志愿者中，尿apo(a)浓度经肌酐水平标准化后与血浆Lp(a)值之间存在高度显著的相关性(p = 0.659；P < 0.0001)。在12名健康志愿者的24小时尿液样本中，以apo(a)片段形式排泄的apo(a)占血浆总apo(a)的0.073%，即121μg apo(a)。我们得出结论，通过apo(a)片段排泄进行的Lp(a)分解代谢占每日Lp(a)分解代谢的比例不到1%。
